1. Field of the Invention
The present invention relates generally to a magnetic head, and more particularly, to a multi-head magnetic head unit for recording and/or reproducing information to and from a card-shaped recording medium at high speed.
2. Description of the Related Art
As a practical matter, the automated reading of information from a card-shaped recording medium such as a commuter rail pass ordinarily must be done at high speed in order to be effective. The reading of information from such a card-shaped recording medium is accomplished by sliding the card-shaped recording medium over the surface of a magnetic head unit containing a plurality of magnetic gap portions that read magnetic information recorded on the recording medium. For convenience, hereinafter such a magnetic head unit containing a plurality of magnetic gap portions is referred to simply as a multi-magnetic head, while the card-shaped recording medium described above is referred to simply as a magnetic card.
It will be appreciated that the surface of the magnetic head that comes into sliding contact with the magnetic card should be made from a material that is resistant to abrasion, and conventionally these surfaces are typically made from one or another such abrasion-resistant material.
FIG. 1 shows an example of a conventional multi-magnetic head for reading a magnetic card, in which an anti-abrasion material member is provided at the surface that contacts the magnetic card. A multi-magnetic head 1 comprises a plurality of pairs of holders 2a, 2b made of a nonmagnetic material, each of the pairs supporting respective halves of a plurality of pairs of magnetic cores 3a, 3b, the pairs of magnetic cores 3a, 3b Joined so as to form gaps 3c therebetween into which gap spacers 9 are inserted, with the whole assembly contained in a shield casing 4. It should be noted that magnetic shields 5 are positioned between each of the pairs of magnetic cores 3a, 3b. Finally, between each of the gaps 3c, that is, between each of the pairs of magnetic cores 3a, 3b exposed in the gap 3c, and each of the magnetic shields 5 an abrasion-resistant ceramic chip 6 is inserted into concavities formed in the holder 2a, 2b for that purpose.
In the case of a magnetic head reading a magnetic card, the edge of the magnetic card hits the magnetic head at high speed. The action of the edge of the magnetic card hitting the magnetic head at high speed, when repeated with a large number of magnetic cards over an extended period of time, causes much wear on the magnetic head, particularly as compared to a case in which a continuous recording medium such as a magnetic tape runs smoothly and continuously over the surface of a magnetic head.
Providing an abrasion-resistant material member between each of the exposed pairs of magnetic cores 3a, 3b and each of the magnetic shields 5 as described above reduces to some extent the impact of the edge of the magnetic card hitting the magnetic head, that is, the exposed pairs of magnetic cores 3a, 3b. However, these abrasion-resistant material members are positioned to the sides of the magnetic head and therefore do not fully blunt the impact of the edge of the magnetic card.
In addition, as more information continues to be stored on the magnetic cards and the number of tracks on the magnetic cards thus continues to increase, so, too, does the number of magnetic heads, that is, magnetic cores, with the result that the number of abrasion-resistant material members positioned between the magnetic cores and the magnetic shields also increases, thus complicating the process of producing the multi-magnetic heads and increasing the cost of production as well.